State Test Standards

Some states have established standards for allowable pollutants for used vehicles. These standards are normally given in CO (percentage) and HC (ppm). Vehicle tail-pipe emissions can be checked against the standard using an exhaust gas analyzer. Typical standards for newer vehicles would be 0.5 percent CO and 200 ppm HC. If vehicle emissions are below this standard, vehicle would pass emissions test. These standards are used to determine if the vehicle is running properly, not to be used for tuning or adjusting the engine. If the vehicle will not pass emission test or is running poorly, use the manufacturer's diagnostic procedures and specifications for repair.

Test standards may change each year and vary from state to state, and even by county within each state. It is not possible to provide an accurate and up-to-date list of emissions standards. Emission standards can be obtained for your area by contacting your local county or state office. Remember, the emission standards are only for test purposes. The manufacturer's adjustment procedures and specifications must be followed when repairing vehicles.